Vaporization of adipic acid and reaction thereof with ammonia to produce adiponitrile



Oct. 13, 1964 'r. M. vEAzl-:Y E'rAl. 3,153,084

VAPORIZATION OF ADIPIC ACID AND REACTION THEREOF WITH AMMONIA TO PRODUCE 111')IPONITRILEIV CON DE MS E R INVENTORS Thomas MVeuzzy Wayne R. Eberh rd1` BY` ,MM 7 7 ATTORNEY PRODUCT RECEIVER T. M. vEAzEY E'rAL 3,153,084

ADIPIC REAC N THEREOF WITH AMMONIA To P IPoN Oct. 13, 1964 VAPORIZATION OF' ACID AND RODUCE AD Filed Sept. 8, 1960 ILE 2 Sheets-Sheet 2 llll/ INVENTORS Thomas MVeclzcy Wayne R. Eber hard? /JM 777. 72,5%

ATTORNEY `llriid States Patent s iss ses y vAronrzArioN oraniric Aem AND anne- 'non rnnaaor wrm Ammonia rro vraonucn annornrr. f

Thomas M. Veazey and Wayne R. Eberhardt, Decatur,

Ala., assignors,` Vby mesne assignments, to Monsanto Coimrany, a corporation of Delaware Filed Sept. 8, 1960, Ser. No. 54,783

6 Ciaims. (Ci. Zeil-465.2)

sumed importance as a valuable intermediate from which hexamethylene diamine canbe prepared, the said diamine and the adipic acid forming` Ythe basic substances employed inthe production of nylon-66 which chemically is polymer-ichexamethylene adipamide. For obvious reasons the hexame'thylene diamine' is the 'more expensive component usedin the preparation of nylon-66. Hence, it is desirable to reduce lthe'c'ost Yof thel diamine `as much as possible. One signicant factor in the expense of producing hexamethylene diamine isthe cost of` purifying the relatively poor grade of adiponitrile which one obtains by the known processes and apparatus. That is, to say, the adiponitrile obtainable according to Aprior art processes must be subjected to expensive puriication procedures prior to its hydrogenation to produce hexamethylene diamine. Prior manufacturing methods 'and apparatus have involved spraying molten adipic acid into a rather large chamber having a wall maintained ata temperature above the boiling point of the acid. The sprayed droplets of adipic acid are brought into contact with theheated Wall. Desirably, the contact of the adipic Aacid with the heated surface induces instant vaporization of the adipic acid A carrier gas of superheated ammoniasweeps the vaporized adipic acid out of the chamber and through heatedconduits to a chambercontaining a dehydrating catalyst wherein the acid and ammonia react to form adiponitrile.

A major vproblem encountered in the manufacture of adiponitrile employing the 'known methods andapparatus describedabove has been the rather extensive degradation Aof adipic acid into decomposition products such as cyclo?y pentanone. In addition side reactions occur, resultingrin theformation of by-products such as 4cyanovaleric acid,

f1(- cyanovaleramide, lcyanocyclopentylideneimine and N adipainide, as well as tars' and elemental carbon. .Ob-

y .viously, such ldegradation not onlyl reduces the yield of the desired product, butalso results, in an impure product which must be subjected to expensive purification procedures.` Furthermore, as a resultjof the formation of degradation'products, besetting problems of `plugging of the catalyst bed and build-upof deposits in the vaporization chamber and the various conduit linesin thevsystem ensue. Investigations made in connection with the above y discussed `problems resulting from the formation of decomposition productsehave ledto the discovery that a mainffactor` in the degradation of adipic acid has been i `not yonly the length of time in which the adipic acid' is maintainedatfelevated temperatures, but also the large surface area of the equipment with which the vaporous 351515,084 feierte@ @Gi-:13; 195.4

in contact with. superheated ammonia in an advantageous manner. In accordance with an additional and beneficial feature of the invention, 'the vaporization of the adipic acid may becarried out in the presence of superheated steam. Preferably the vaporization lof adipic acid and contact thereofV with ammonia, together with steam if desired, occur directly above-the bed ofcatalyst employed to speed the reaction between the adipic'acidV and am-`- mronia.` Byyirtue of apparatus -a separate vaporization chamber and accompanying conduits from it toa catalytic chamber areelimin'ated. Furthermore, vaporization of adipic acid and conversion thereof to adiponitrile are conducted in a single unit comprised of contiguous vaporizer and converter sections. VNot only does this represent a considerable economic saving inthe cost of equipmentconstruction, but also results in such rapid and eiiicacious vaporization and such reduced surface area contact of equipmentl and Vaporous adipic acid so as to minimize greatly the formation of tars and other decomposition products resulting from the degradation Iof adipic acid.

Noreover, by employing the process" of this inventiom yields of ladiponitrile with a higher degree of purity have been increased substantially over yields heretofore ob= tamable byusing the methods andv apparatus ofthe prior "Itis, therefore, a primary objects of this invention to provide a novel method for improved manufacture of adiponitrile. t I

It is a further object of this inventiontoprovide a novel.

method wherein the vaporization of adipic. acid and th reaction thereof with ammonia to form adiponitrile are conducted in a substantially unitary apparatus.

It isa further object of this invention to provide a novel method for the preparation of adiponitrile from adipic acid and ammonia in high yields and with a minimum formationy of degradation products. r r p Another object. of this invention is to provide a novel method for converting adipic acid vapor in the presence of ammonia and steam in a rapid, eicientfand economi.

cal manner. i

Yet another object of this invention is to provide a novel method wherein the time between -the point at which the, adipic acid and ammonia initially contact each other and the point at which they contact the dehydrating catalyst is reduced to a minimum.`

Other objects and advantages of the invention Awill be- `come apparent from the following description thereof taken in connection with the accompanying drawing.

In accordance with the invention in 'its'preferre'd ern-v bodiments fthe 'method 'includes establishing a flowing,

v stream lof` molten adipicy acidthrough asmall opening adipicl acid comesinto`contact. An additional drawback f 'of Athe prior art systems `is Vthat the equipment employed represents a considerable investment and is expensive to and discharging same into an annular zone, preferably the zone assuming the form of a truncated cone. In a speciic embodiment the discharge ismade axially into; said zone at a pointnear the smaller end thereof. A stream of superheated ammonia is established and is directed into said zone so that the ammonia moves concurrently and concentrically With `respect to the stream of molten ladipic acid. A`Theresulting concentric streams of acid and ammonia are drectedforthwith intoV an expansion zoneto vaporize Vthe adipic acid. The expansion zone preferably u assumes the form of Ya second truncated cone, the cones'V being interconnected at their smaller endsby means of a cylindrically'shaped connectingzonerv The thus-expanded material isipassed directly over a catalytic bed Vatan elevatedtemperature to convert the adipic acid into adiponitrile. Finally, the Vthus-produced adiponitrile is condensed and'collected. AIn accordance with a preferred feature of the invention the stream of superheated ammonia enters 'the first annular zone tangentially near the larger end thereof; Moreover, a stream "of superheated steam may be flowed into the zone simultaneously with the superheated ammonia. In one aspect of the invention, a stream of superheated ammonia and a stream of superheated steam enter the irst annular zone tangentially near the larger end thereof at points about 180 apart.

The novel features which are believed to be characteristie of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and mode of operation, may be understood best by reference to the following description taken in conjunction with the accompanying drawing in which:

FIGURE l is a vertical view partly in section of adipic acid converting apparatus with associated structure being shown lschematically for purposes of illustration;

FIGURE 2 is a sectional view taken along line 2 2 f of FIGURE 1 in the direction of the arrows; and

FIGURE 3 is an enlarged section view of the nozzle block shown schematically in FIGURE 1.

Referring now to the FIGURE 1 of the drawing, there is shown a suitably supported chamber 1t) which encloses four catalyst-containing tubular members 12. A catalytic material 13 is incorporated in these elongated tubes. The level to which the tubes are filled will depend on the size of the tubes, the flow rate of the reactants through the catalyst bed, etc. While one such tube may be employed, it is preferred to use a plurality of tubes. The tubular members 12 at their upper ends communicate with an upper compartment 14 dened by'a wall 15. At

,theirV lower ends the tubular members 12 communicate with a lower compartment 16 defined by a wall 17. A suitable mesh screen 18 or. like porous material supports Y the catalytic material 13 inthe said tubular members.

" 24 and vessel 20 of the apparatus and preferably is adapted to be filled with a suitable heating medium such as Dowtherm vapors or the like. It is apparent that this heating shell also may take theform of other conventional heating means, the objective being toy maintain the block 24 and vessel 20 at a suitably high temperature ordinarily sutlicient tol vaporize adipic `acid in a rapid and eiiicient manner. Y

. With reference to the disclosed means for transferring heat to the tubular members 12 and to the reaction mass moving in a gaseous phase therethrough and in `contact with the catalytic materialv 13, there is shown a container 29 preferably encased inan insulatingfmaterial 3)A and .adaptedv for holding a heating fluid 32 such as a liquid having a `high boiling point. The heating fluid preferably ills the container to the level indicated and surrounds the vtubular members 12 in heat exchange relationship, therewith. A baffle plate 34V as disclosed suitably supported within the container 29 separates the area in which the tubular members are disposed from the pie-shaped-area in which heat is suppliedv to the Vheating iluid. While heat may be supplied to the fluid in other conventional manners, it hasv been found convenient t do this by-providing within the heatingarea heating `means 36. The heating means preferably comprises an internal electrically energizable heater element, electrical power beingsupplied thereto through conductive lines 38 for receiving electric power. The yheating means extends through the bottom of container 29 and upwardly into the heating iluid 32 in the pie-shaped area to maintain the same at a desired elevated temperature. To provide eliicient circulation of the fluid apropeller blade type agitator 40 is iixedly mounted to a shaft 42 adapted to be rotated by a motor 44. The pitch of the blade of the agitator is such thatthe fluid moves downwardly through the heating area and upwardly through the area in which the tubular members 12 are located.

Connecting the lower compartment 16 with a condenser chamber is a conduit 46, in which chamber the reaction product moving from the lower compartment 16 is cooled so as to condense the adiponitrile produced. A product receiver is connected with line 4S for collecting the condensed material from which the material may be transmitted for further processing such as purification and/or hydrogenating procedures. The receiver may be equipped with an Off gas conduit Si) for removal of ammonia and other waste gases.

Referring to the structure in FIGURE 1 for supplying the feed materials to the apparatus, there is shown schematically an adipic acid supply conduit 52 leading to a point near the center of nozzle block 24. This conduit, as well as other feed lines, may be surrounded by heating elements for insuring that the adipic acid entering the block is in a molten condition and is equipped with an insulation jacket. An ammonia supply conduit 54 extends through a superheater' before connecting with the nozzle block 24 so that the ammonia is heated prior to its contact with adipic acid to a suitably high temperature. A steam supply conduit 56 extends through a superheater before connecting with the nozzle block 24 so that the steam is heated prior to its contact with adipic acid to a suitably high temperature.

The feed sources for the three components of reaction in the instant invention have not been disclosed in the drawing but comprise conventional feed means. For instance, a melt and feed tank for molten adipic acid may be provided; and a feed pump may be used to move the acid to the nozzle block 24. Ammonia can be fed to the superheater from a conventional high pressure cylinder. i

With reference now to the particular structure of the nozzle block 24, attention is directed to FIGURE 3 0f the drawing. In the embodiment shown three nozzles extend within the .block 24, namely ammonia supply nozzle 58, adipic acid supply nozzle 60, and steam supply nozzle 62 fitted in-threaded relation with the block 24. Reference numerals 64, 66, a'ncll 68 indicate thermocouples extending within the respective nozzles and which are operatively connected with a control means (not shown) `for regulating the temperatures of the superheaters and adipic acid melt tank as desired in response to temperature variations in the nozzles.

Adipic acid supply nozzle 60 terminates in a taper nose 70 preferably of conical shape and extends into an annular zone '72' which assumes the form of a truncated cone. The tip of the nose 7.0 extends to a point near the smaller endof the frusto-conical annular zone. Communicating with the zone 72 are port means 74 and 76 for supplying superheated ammonia and superheated steam, respectively, to the said annular zone. In accordance with one embodiment of this invention the ports are located so as to provide a tangential entry of the ammonia and the steam into the zone 72.- Connecting the smaller end of the zone 72 with' a second frustoconical annular zone 78 is a cylindrical portion 80. The zone 78 provides a convenient flaring exit .so .that the adipic acid and the attendant gases expand and flow into the expansion chamber 22.

, In operation .the tubular members v12 are lilled with a dehydrating` catalyst and the uid surrounding the members is heated to adiponitrile forming temperatures.. The block 24 and chamber 22 are heated to desired temperatures, so as to insure rapid vaporization `of the adipic acid. Molten adipic acid is pumped to nozzle 60 and downwardly therethrough and is emitted from the nose of the nozzle into the annular zone 72 in the form of a o p y, Y 'fine liquid spray. .At the Y'same time, superheated arnmonia is supplied to nozzle 58 and by way of port means 74 and enters the Zone'72 at a point near the top thereof.

As can be seen the ammonia will be directed in impinging' relationagainst nose 70 downwardly in concentric and concurrent relation with the emitted stream of adipic acid. If the port means 74 is in a orrn of a tangential feed pipe', a rotary motion of the ammonia or a cyclonjc cufrent of the ammonia is set up in the zone 72,` providing a more intimate contact between the adipic acid and ammonia. Simultaneously, superheated steam may mbe supplied to nozzle 62 and by way of port means 76 `enters the zone 72 at a point near the top thereof.' The steam Awill be directed downwardly with the ammonia in `concentric and concurrent .relation with the emitted stream of adipic acid. Here again the port means 76 may take the form of a tangential feed pipe in which event a cyclonic current of the ammonia-steam mixture is set up. In some cases it is preferred that the tangential entry ofthe ammonia be about 180 apart from the :tangential entry Zoftherstea'rn. The resulting concentric .streams are directed downwardly through a cylindrical portion or zonet) interconnecting the first frusto-conical annularzone 72withvthe second frusto-conical zone 73 at `their smaller ends and thence through the said second zone to expand the stream and `toinduce Vaporization of the adipic acid. Next, the `thus-,er/rpanded material is flowed downwardly over a 'dehydrating catalyst contained in members 12 at any elevated temperature to convert the adipic acid and ammonia into high grade adiponitrile. The thus-produced adiponitrile is separated from the. catalyst and condensed.

The dehydration catalystswhich may be employedA for adiponitrile arewell known in. the art and include for example the dehydrating oxides of aluminum, silicon, tungsten, titanium, molybdenum, and the like. A catalyst yielding excellent results is'afsintered mixture of boric variables are:l Y

o (l) `Ammoniaiadipic acid ratio V(2) Steamiadipic acid ratio ,(3) SVH (4) `Ratio of vapor1zer area to` catalyst area (5) Converter temperature (6) Vaporizertemperature l Withregard `to the ammoniatadipic acid ratio, it has ,been found that best results are achieved by employing ,a iiow ratio betweenf0-65 anda 1.5 on a weight basis with the preferred range being between 0.8 and 1.3.v At ratios .less than 0.65 it has been found vthat reaction rate slows down perceptively, while no advantage is served byern'- ployingammonia in excess of 1.5.

The use of steam is not essential to the operation` of ,theinstant process; butithas been found that theuse of steam notably decreases degradation of the process materials and increases catalyst life.` Howeveryadipo- .nitrile yields -have been found to decrease substantially asathe steamtadipic acid ratio is raised muchhabove 0.2 ...on a weightb'arsis, VAccordingly, the steam'adipic acid ratiol should lbernaintained at about 0.2 or less.`

` thev conversion of ammonia and adipic acid mixtures to Vously employed.

aredirectlyV related to Vany specific temperaturefand pressure to SVH are (1) contact time of the reactants .with

the catalyst, and (2) retention time of the reactants within the vaporizer sectionrof. the apparatus. The value of SVI-[must be maintained suiciently low sol as to give good Contact time with the catalyst and completeness of reaction, but onthe other hand not so low as to result a long retention time *within the vaporizer section of the converter which `might ,result g in increased adipic acidk degradation. Generally, satisfactory results have been obtained using theV `SVH values between 300 and 600. The 4preferred range is between 350 and500. When employing these values, it has been found that kretention time within the vaporizer section may be up to five seconds and more, although highest yields are `obtained with a retention time of less than one second. It is believed `that the rapid flow of reactants with consequent short retention time within the vaporizing sections as well as low surface areaof the vaporizver leads to considerably less degradation as compared to the degration obtained by the use of the large volume'vaporizer chambers previ- Withregard to variablesNos. 5 and'6, it has been found that the temperatures of the converter andthe vaporizer sections are generally maintained substantially the Asame ranges. `Temperaturesbetween 330 C. and 410 C. have been found to give the best results with the preferred temperature of the converter being maintained at about 37 0'410 C. and the preferred temperature of the vaporizer section being held between Y 345 C. and 400 C. 1 l

The following examples are given for purposes of illusf tration and are not to be construed as being'limited thereto. In these examplesparts and percentages are given on` a vweight basis'unless"otherwiseindicated 1 `Example l y Employing the apparatus illustrated in the drawing, the dehydrating catalyst Vtemperature was brought to and maintained at 390 C., while `the vaporizer section was maintainedrat 3353. Molten adipic acid at i198i2- C.

wasted through the nozzle head at a rate of16.8 pounds j per hourjwherev it 'contacted superheated ammonia at a temperature of 450i2 C. being fed at a rate of 11.9

pounds per hour. No steam was fed to the processi. vThe o ammoniaadipic acid Vratio was 0.71 and SVH was,` 420.l

The dehydrating catalyst was a sintered mixture of boric acid and phosphoric acid. The ,process was stopped just short of four hours when a total of,66,97 pounds of adipic acid had been fed to the converter. The crude product,

" which had been continuously condensed was fractionally i distilled. The yield Iof adiponitrile was 93.20 percent of "theoretical.

VariableNo. 3 above, i.e'., SVH, also referred to as Vspace velocity]s is the ratio of the total volume `of re- `actantspassing through the system calculated as being in vapor phase at 0.C. and 760 mm. Hgabsolute pressure tothe total apparent volume ofthe catalyst (i.e., the lled volume ofthe container in which the catalyst is con'- Vtained). Two dependent variables not listed above which .i Example `ll A In this run, the catalyst and' vaporizerttemperatures v.were thesame as in Example I. Superheatedammonia at 450 *l C. VVand molten adipic acid at 180'i6 C. were fedzto the reactor'at 11.1 andy 10.3 pounds per hour respectively until atotal of 43.20 pounds of adipic acid had been supplied. "The ammniaadipic acid nratiolwas maintained at l'.08.[` SVH was 3*'73. Thesame catalyst as in Example I was used.V 40.28 pounds of adiponitrile was recovered for a yield ofv 93.24 percent of theoretical.

Example III u Superheated ammonia at 45li5" C. was fed `atthe Y rate of'l22ypou`nds Aper hour to kthe nozzler blockV where it meti'onconiing streams of molten adipic acid at 21.61-6" C. fed at the ratel of'l0.l`'pounds per hourhnd superheated `'steam Aat "A701-1:8" C. fed at vthe rate ofl2;0ppounds f (water) per -hou'rf' A total of 39.37. poundsof adipic acid was reactedg-` The above quantities Vgave an` .ammof niafa'dipic acid ,ratio of 1.20 and a steamradipic `acid lratio of 0.19. SVH was 463, vaporizer temperature was 335 C. and the converter temperature wasmaintained hour. respectively, without steam addition.

.acid fed Vto ythe reaction, for ay Vantrace/t at 390 C. Thesarne catalyst as abovein Example I was used. A 94.85 percent lof theoretical yield of adiponitrile was obtained.

The following examples are vpresented to demonstrate that the high adiponitrile yields in the preceding three examples were made possible by the compact vapon'zer described in this invention, and that the high yields are Example IV Employing a vaporizing apparatus with 2.5 times the volume and 4.2 times the surface area of the apparatus y.described in this invention, the temperature of the converter was brought to and maintained at 390 C., while the vaporizer section was maintainedat 330 C. Molten adipic acid and superheated steam were fed through the nozzle head at 3.08 and 2.28 pounds per hour, respectively. No steam was fed to the system. The ammonia: adipic ratio .was 0.74, and the SVH was 426. The standard boric-vphosphoric acid mixture catalyst was used in the converter. A total of 12.2 pounds. of adipic acid were ,.fed to the reaction, .and ta yield of only k69.7 percent of `theoretical was obtained.

' i Example V The vaporizer apparatus, catalyst, vaporizer andconverter temperatures were the same as in Example IV.

Superheated ammonia was fed to the reaction at 2.56 pounds per hour, and molten adipic acid at 2.02 pounds per hour until 8.06 poundsadipic had been fed. rThe action for a .yield of 85.4 percent of theoretical.

Example VI The same vaporizer apparatus, catalyst, vaporizer and converter temperatures given in Example IV were employed in this example. Superheated :ammonia and mol- 'ten adipic acid were fed at 3.35 and A2.87 pounds per The kammonia:adipic acid ratio Was 1.13 and the SVH was 446. A yield vof 80.4 percent of theoretical was obtained by recovering 6.83 pounds of ladiponitrile from the 11.48

pounds of adipic acidfed to the reaction.

Example VII A large vaporizer with 178 times fthe volume and 43.6Y

fed at 2.46 pounds per hour; superheated steam at 550 "C, was fed at 2.27 pounds per hour; and molten adipic acid ati-276 C. .was fed at 2.54 pounds per hour. The

standard'boric-phosphoric acid catalyst mixture was used in the converter." The SVI-Iwas 790. 4.84 pounds of adiponitrile was recovered from 10.18 pounds of adipic yield of 64.2 percent of theoretical.

Example VIII TheA same vaporizer apparatus, catalyst,.vaporizerand converter temperature given in Example VII were used in this example.- Superheated ammonia at 455 C. and molten adipic acid at 250 C. were fed to the vaporizer at 3.08 vand-1.14 pounds per hour respectively. No steam was fed. The' ammoniazadipic lacid ratio `was 2.7, and

the SVH was v518. 9.12 pounds of adipic'acid was fed,

and.4.17 pounds of adiponitrile was recovered, for a yield of 61.8 percent Of theoretical.

'8 Example IX I standard catalyst type was Vmaintained at 350 C. Superheated ammonia at 450 C. was fed `aft 3.39 pounds per hour, and molten adipic `acid at 225 C. was fed at 1.42 pounds per hour, providing an ammoniazadipic acid ratio of 2.39, and an SVH of 573. There was noi steam addition. A yield of 58.3 percent of theoretical was obtained by recovering 4.89 pounds of adiponitrile from 11.34 pounds of adipic acid fed to the reaction.

In the above Examples I-IlI yields of adlponitrile are Y shown .tto be substantially higher than generally heretofore attainable. The loss of yield was found to be attributable primarily to (l) mechanical loss of product in transfer and distillation opera-tions, (2) scale errors, and

tion. Only a minor portion of the -yield loss' was due to decomposition of adipic acid or to reaction products leaving ltar deposits on thecatalyst or in other parts of the system. Moreover, catalyst life was quite prolonged.

In Examples lV-IX, the yield loss was primarily due to decomposition ofl reactants in the Vvaporizer section. Tars were formed which deposited on the catalyst and substantially reduced the effective life of the catalyst. As many different embodiments of this invention may be made without departing from the spirit :and scope thereof, it is to be [understood that fthe invention is not limited to the specific embodiments disclosed herein except as defined in the following claims.

What is claimed is:

1. A process for the vaporization of adipic acid and reaction thereof with ammonia'to form adiponitrile comprising the steps of flowing a molten stream of adipic acid through a small opening axially into an annular zone, establishing a stream of superheated ammonia moving concurrently and concentrically with respect to the stream of adipic acid, expanding and heating the concentric streams of adipic acid and ammonia to vaporize the adipic acid, flowing the thus-expanded material over a dehydrating catalyst at an elevated temperature to convert the adipic acid and ammonia into adiponitrile, and condensing the thus-produced adiponitrile.

2. A process for the vaporization of adipic acid and reyaction thereof with ammonia to form adiponitrile comprising the steps of flowing a molten stream of adipic acid through a small opening and discharging same axially into aV frusto-conical annular .zone near the smaller end thereof, establishing a stream of superheatedl ammonia entering said zone near the larger end thereof and moving concurrently and concentrically with respect to the discharged stream of adipic acid, heating .and directing the resulting concentric streams into' the smaller end of a second frusto-conical annular zone to expand the streams and to induce vaporization of'the adipic acid, flowing the thus-expandedmaterial over a dehydrating catalyst at an elevated temperature to convert the adipic acid and ammonia into adiponitrile,fand condensing the thus-produced adiponitrile.

, 3. A process for the vaporization of adipic acid and reaction thereof with ammonia to form adipom'trile comprising the steps of liowing a molten stream of adipic acid through a small opening and discharging same axially into a truste-conical annular zone nearvthe smaller end thereof, establishing a stream of superheated ammonia entering said zone near the larger end thereof and moving concurrently and concentrically with respect to the dischargedstream of adipic acid, heating and directing the resulting concentric streams through a cylindrical zone interconnecting the rst frusto-conical annular zone and a second frusto-conical zone at their smaller ends and thence through the said second zone to expand the streams and to induce vaporization of the adipic acid, owing the `thus-expanded material over a dehydrating catalyst at ammonia into adiponitrile, and condensing the thus-prolduced adiponitrile after separating same from the said Vstreamsdownwardly through a cylindrical zone interconnecting the first truste-conical annular zone and a second truste-conical zone at their smallersends and thence through the said second zone to expand the streams and to induce vaporization of the adipic acid,

iiowing thev thus-expanded material downwardly over a `'.lehydrating catalyst at an elevated temperature to convert the adipic acid and ammonia into adiponitrile and condensing VVthe thus-produced adiponitrile after separating same from the said catalyst.

5. A process for the vaporization of adipic acid. and reaction thereof with ammonia to form adiponitrile comconical zone and a second frusto-conical zone at their prising the steps of owing a molten stream of adipic acid through` a small opening and discharging same downwardly and axially into a irst frusto-conical annular zone Y near the smaller end thereof, .establishing a stream of superheated ammonia enteringA said zone tangentially near the larger end thereof, establishing a stream of superheated steam entering said zone tangentially near the larger end thereof and at a point about 180 from the point of entry of the ammonia, heating and moving the streams of ammonia and steam concurrently and concentrically with respect to the discharged stream of adipic acid downwardly through the first annular zone and then through a cylindrical zone interconnecting the rst frustosmaller ends and thence through the said second zone t0 expand the streams and to induce vaporization of the adipic acid, flowing the thus-expanded material downwardly over a dehydrating catalyst at an elevated temperature to convert the adipic acid and ammonia into adiponitrile, and condensing the thus-produced adiponitrile after separating same from the catalyst.

6. A process for the vaporization of adipic acid and reaction thereof with ammonia to form adiponitrile comprising the steps of lowing a molten stream of adipic acid through a small opening and discharging same downwardly and axially into an annular zone, establishing a stream of superheated ammonia moving concurrently and concentrically with respect to the stream of adipic acid, the flow rate of ammonia to adipic acid having a weight ratio between 0.65 and '1.5, expanding and heating at a temperature of E330-410 C. the concentric streams of adipic acid and ammonia to Vaporize the adipic acid, flowing the thus-expanded material over a dehydrating catalyst at a temperature between S-410 C. to convert the adipic acid and ammonia into adiponitrile, and thereafter condensing the thus-produced adiponitrile.

References Cited in the file of thispatent UNITED STATES PATENTS 1,368,346 Moisant Feb. 15, 1921 1,406,058 Moisant Feb. 7, 1922 2,273,633 Fluchaireet al. Feb. 17, 1942 2,747,974 Folger May 29, 1956 2,854,320 Fields Sept. 30, 1958 2,872,297 Dugan Feb. 3, 1959 2,904,409 Bolstad Sept. 15, 1959 2,910,502 Hoaglin et al. Oct. 27, 1959 2,955,130 Guyer et al. ct'. 4, 1960 2,964,553 Duxbury et al. Dec. 13, 1960 

1. A PROCESS FOR THE VAPORIZATION OF ADIPIC ACID AND REACTION THEREOF ITH AMMONIA TO FORM ADIPONITRILE COMPRISING THE STEPS OF FLOWING A MOLTEN STREAM OF ADIPIC ACID THROUGH A SMALL OPENING AXIALLY INTO AN ANNULAR ZONE, ESTABLISHING A STREAM OF SUPERHEATED AMMONIA MOVING CONCURRENTLY AND CONCENTRICALLY WITH RESPECT TO THE STRESS OF ADIPIC ACID, EXPANDING AND HEATING THE CONCENTRIC STREAMS OF ADIPIC ACID AND AMMONIA TO VAPORIZE THE ADIPIC ACID, FLOWING THE THUS-EXPANDED MATERIAL OVER A DEHYDRATING CATALYST AT AN ELEVATED TEMPERATURE TO CONVERT THE ADIPIC ACID AND AMMONIA INTO ADIPONITRILE, AND CONDENSING THE THUS-PRODUCED ADIPONITRILE. 